Apparatus and method for real-time sensing of properties in industrial manufacturing equipment

ABSTRACT

An apparatus and method for real-time sensing of properties in industrial manufacturing equipment are described. The sensing system includes first plural sensors mounted within a processing environment of a semiconductor device manufacturing system, wherein each sensor is assigned to a different region to monitor a physical or chemical property of the assigned region of the manufacturing system, and a reader system having componentry configured to simultaneously and wirelessly interrogate the plural sensors. The reader system uses a single high frequency interrogation sequence that includes (1) transmitting a first request pulse signal to the first plural sensors, the first request pulse signal being associated with a first frequency band, and (2) receiving uniquely identifiable response signals from the first plural sensors that provide real-time monitoring of variations in the physical or chemical property at each assigned region of the system.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/104,335, filed Aug. 17, 2018, which is based up and claims thebenefit of priority from U.S. Provisional Patent Application No.62/546,882, filed on Aug. 17, 2017, entitled “APPARATUS AND METHOD FORREAL-TIME SENSING OF PROPERTIES IN ELECTRONIC DEVICE MANUFACTURINGEQUIPMENT”, and U.S. Provisional Patent Application No. 62/627,614,filed on Feb. 7, 2018, entitled “APPARATUS AND METHOD FOR REAL-TIMESENSING OF PROPERTIES IN INDUSTRIAL MANUFACTURING EQUIPMENT”; the entirecontents of which are incorporated herein by reference.

FIELD OF INVENTION

The present invention relates to an apparatus and method for monitoringa process in a processing system and, more particularly, to monitoring aprocess using a monitoring device having an integral sensing andtransceiving device. More specifically, the invention relates toreal-time sensing of properties in industrial manufacturing, such assemiconductor device manufacturing.

BACKGROUND OF THE INVENTION

The fabrication of integrated circuits (IC) in the semiconductorindustry typically employs plasma to create and assist surface chemistrywithin a plasma reactor necessary to remove material from and depositmaterial to a substrate. In general, plasma is formed within the plasmareactor under vacuum conditions by heating electrons to energiessufficient to sustain ionizing collisions with a supplied process gas.Moreover, the heated electrons can have energy sufficient to sustaindissociative collisions and, therefore, a specific set of gases underpredetermined conditions (e.g., chamber pressure, gas flow rate, etc.)are chosen to produce a population of charged species and chemicallyreactive species suitable to the particular process being performedwithin the chamber (e.g., etching processes where materials are removedfrom the substrate or deposition processes where materials are added tothe substrate).

During, for example, an etch process, monitoring the plasma processingsystem can be very important when determining the state of a plasmaprocessing system and determining the quality of devices being produced.Additional process data can be used to prevent erroneous conclusionsregarding the state of the system and the state of the products beingproduced. For example, the continuous use of a plasma processing systemcan lead to a gradual degradation of the plasma processing performanceand ultimately to complete failure of the system. Additional processrelated data and tool related data will improve the management of amaterial processing system and the quality of the products beingproduced.

SUMMARY

Techniques described herein pertain to an apparatus and method formonitoring a process in a processing system and, more particularly, tomonitoring a process using a monitoring device having an integralsensing and transceiving device. More specifically, the inventionrelates to real-time sensing of properties in industrial manufacturing,such as semiconductor device manufacturing.

According to various embodiments, an apparatus and method for real-timesensing of properties in industrial manufacturing equipment aredescribed. The sensing system includes first plural sensors mountedwithin a processing environment of a semiconductor device manufacturingsystem, wherein each sensor is assigned to a different region to monitora physical or chemical property of the assigned region of themanufacturing system, and a reader system having componentry configuredto simultaneously and wirelessly interrogate the plural sensors. Thereader system uses a single high frequency interrogation sequence thatincludes (1) transmitting a first request pulse signal to the firstplural sensors, the first request pulse signal being associated with afirst frequency band, and (2) receiving uniquely identifiable responsesignals from the first plural sensors that provide real-time monitoringof variations in the physical or chemical property at each assignedregion of the system.

According to an embodiment, an apparatus for real-time sensing ofproperties in industrial manufacturing equipment is described. Theapparatus includes: first plural sensors mounted within a processingenvironment of a semiconductor device manufacturing system, wherein eachsensor is assigned to a different region to monitor a physical orchemical property of the assigned region of the system; and a readersystem having componentry configured to simultaneously and wirelesslyinterrogate the first plural sensors using a single high frequencyinterrogation sequence that includes (1) transmitting a first requestpulse signal to the first plural sensors, the first request pulse signalbeing associated with a first frequency band, and (2) receiving uniquelyidentifiable response signals from the first plural sensors that providereal-time monitoring of variations in the physical or chemical propertyat each assigned region of the system, wherein the first plural sensorsare made operable in the first frequency band according to design rulesthat permit the simultaneous interrogation without collision between theresponse signals echoed from each sensor operating in the firstfrequency band.

According to another embodiment, an apparatus for real-time sensing ofproperties in industrial manufacturing equipment is described. Theapparatus includes: a sensor arranged in a processing environment of asemiconductor device manufacturing system, the sensor comprising: anoscillation circuit responsive to a request signal at an interrogationfrequency that provides a response signal corresponding to a variationof a physical or chemical property of a region of the electronic devicemanufacturing system where the sensor is mounted; and a protective layercovering the oscillation circuit to insulate the sensor from theenvironment present in the electronic device manufacturing system.

Of course, the order of discussion of the different steps as describedherein has been presented for clarity sake. In general, these steps canbe performed in any suitable order. Additionally, although each of thedifferent features, techniques, configurations, etc. herein may bediscussed in different places of this disclosure, it is intended thateach of the concepts can be executed independently of each other or incombination with each other. Accordingly, the present invention can beembodied and viewed in many different ways.

Note that this summary section does not specify every embodiment and/orincrementally novel aspect of the present disclosure or claimedinvention. Instead, this summary only provides a preliminary discussionof different embodiments and corresponding points of novelty overconventional techniques. For additional details and/or possibleperspectives of the invention and embodiments, the reader is directed tothe Detailed Description section and corresponding figures of thepresent disclosure as further discussed below.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A through 1C illustrate a schematic representation of anapparatus for real-time sensing of properties in industrialmanufacturing equipment according to an embodiment;

FIG. 2 provides a flow chart illustrating a method for real-time sensingof properties in semiconductor device manufacturing equipment accordingto an embodiment;

FIG. 3 depicts a representative view of a surface acoustic wave (SAW)sensor according to an embodiment;

FIGS. 4A through 4D exemplify response signals following interrogationof plural sensors according to an embodiment;

FIG. 5 depicts a representative view of a SAW-tag sensor according toanother embodiment;

FIGS. 6A and 6B exemplify response signals following interrogation ofplural sensors according to an embodiment;

FIG. 7 depicts a representative view of a SAW-tag sensor according toyet another embodiment;

FIG. 8 exemplifies response signals following interrogation of pluralsensors according to an embodiment;

FIG. 9 exemplifies response signals following interrogation of pluralsensors according to an embodiment;

FIG. 10 depicts an antenna according to an embodiment;

FIG. 11 depicts a method of fabricating a sensor on a substrateaccording to an embodiment;

FIG. 12 depicts a method of fabricating a sensor on a substrateaccording to another embodiment;

FIG. 13 depicts a method of fabricating a sensor on a substrateaccording to another embodiment;

FIG. 14 depicts a method of fabricating a sensor on a substrateaccording to another embodiment;

FIG. 15 depicts a method of fabricating a sensor on a substrateaccording to another embodiment;

FIG. 16 depicts a method of fabricating a sensor on a substrateaccording to yet another embodiment; and

FIGS. 17A through 17D provide schematic illustrations of plasmaprocessing systems for performing the method of etching according tovarious embodiments.

DETAILED DESCRIPTION

Techniques described herein pertain to an apparatus and method formonitoring a process in an industrial manufacturing system and, moreparticularly, to monitoring a process using a monitoring device havingan integral sensing and transceiving device. The manufacturing systemcan include a semiconductor manufacturing system. The manufacturingsystem can facilitate manufacturing of semiconductor devices, photonicdevices, photo-emission devices, photo-absorption devices, orphoto-detection devices. The manufacturing system can include anon-semiconductor manufacturing system. The manufacturing system canfacilitate manufacturing of metallic, semi-metallic, or non-metallicworkpieces. The manufacturing system can facilitate manufacturing ofmetallic, polymeric, or ceramic workpieces. The manufacturing system canfacilitate manufacturing of glass or glass-like workpieces.

According to various embodiments, an apparatus and method for real-timesensing of properties in industrial manufacturing equipment, such assemiconductor device manufacturing equipment, are described. The sensingsystem includes plural sensors mounted within a processing environmentof a semiconductor device manufacturing system, wherein each sensor isassigned to a different region to monitor a physical or chemicalproperty of the assigned region of the manufacturing system, and areader system having componentry configured to simultaneously andwirelessly interrogate the plural sensors. The reader system uses asingle high frequency interrogation sequence that includes (1)transmitting a first request pulse signal to the first plural sensors,the first request pulse signal being associated with a first frequencyband, and (2) receiving uniquely identifiable response signals from thefirst plural sensors that provide real-time monitoring of variations inthe physical or chemical property at each assigned region of the system.In particular, a wafer-type sensor of a circuit capable of eliminatingthe need for a wired power supply, to comply with automationrequirements, capable to withstand heat transfer due to ionic impact andmeasuring the temperature distribution on a wafer, among other things,is described in various embodiments.

According to an embodiment, an apparatus 100 for real-time sensing ofproperties in semiconductor device manufacturing equipment is describedand depicted in FIGS. 1A through 1C. The apparatus 110 includes: firstplural sensors 2A, 2B (see FIG. 1B) mounted within a processingenvironment 115 of a semiconductor device manufacturing system 100,wherein each sensor 2A, 2B is assigned to a different region to monitora physical or chemical property of the assigned region on a workpiece 1(or substrate); and a reader system 120 having componentry configured tosimultaneously and wirelessly interrogate the first plural sensors usinga single high frequency interrogation sequence. The interrogationsequence can include (1) transmitting a first request pulse signal tothe first plural sensors, the first request pulse signal beingassociated with a first frequency band, and (2) receiving uniquelyidentifiable response signals from the first plural sensors that providereal-time monitoring of variations in the physical or chemical propertyat each assigned region of the system, wherein the first plural sensorsare made operable in the first frequency band according to design rulesthat permit the simultaneous interrogation without collision between theresponse signals echoed from each sensor operating in the firstfrequency band. Sensor system 10 can include the plural sensors 2A, 2Bmounted on workpiece 1. Workpiece 1 can be arranged within theprocessing environment 115 of the semiconductor device manufacturingsystem 100, wherein the first plural sensors 2A, 2B are mounted on theworkpiece 1 (see FIG. 1B). The number of sensors in the first pluralsensors can exceed 15 sensors, preferably more than 30 sensors,preferably more than 45 sensors, and more preferably more than 60sensors.

Semiconductor device manufacturing system 100 can include a holder 130,which may or may not include a clamping mechanism, such as a mechanicalclamping system or an electrical clamping system (e.g., ESC,electrostatic chuck). In response to signals from a control system 140,a holder control system 130 can adjust properties affecting theprocessing of workpiece 1, or production workpiece (not shown).Embodiments can include temperature control elements spatially orientedto affect process conditions in different regions of workpiece 1, or aproduction workpiece. Alternatively, gas flows, and other processingproperties, e.g., pressure, plasma power, bias power, etc., can beadjusted in response to signals from control system 140.

In some embodiments, processing environment 115 includes a gas-phaseenvironment without plasma. In other embodiments, processing environment115 includes a gas-phase environment with plasma.

The first frequency band can include an excitation frequency in the 2.45GHz-centered ISM band, as an example, however, other frequency bands arecontemplated. The frequency band can be selected to permitelectromagnetic wave propagation between the reader system and theinstrumented substrate.

The semiconductor device manufacturing system can include an etchingsystem, a deposition system, a plating system, a cleaning system, anashing system, a thermal treatment system, a lithographic coatingsystem, or a polishing system, or other semiconductor processing system.FIGS. 17A through 17D depict several gas-phase and/or plasma processingsystems, within which the sensor system can be implemented.

As further described below, depending on the environment within whichthe instrumented substrate will be exposed, several techniques areproposed to protect the sensor(s). Protective layers, deposited orformed over the sensor, are examples of the protection provided to asensor in an erosive and/or corrosive environment.

According to various embodiments, multiple sensor groupings are assignedto plural, uniquely defined frequency bands, wherein the multiple sensorgroupings including the first plural sensors assigned to the firstfrequency band (to be described in greater detail below). The number ofsensors assigned to a sensor grouping and associated frequency band maynot exceed 25 sensors; however, more or less are contemplated. Eachsensor can include a surface acoustic wave (SAW) delay line device orSAW resonator. The SAW devices can be mounted on workpiece 1 exhibitingan electromechanical coupling coefficient greater than or equal to 1%,or 2 to 3%. And, the substrate can include LiNbO₃, LiTaO₃, orLa₃Ga₅SiO₁₄. Other materials for conducting surface acoustic waves arecontemplated. Lithium niobate or lithium tantalite may be used for lowertemperature operations, and langasite (La₃Ga₅SiO₁₄) may be used forhigher temperature operations. The physical or chemical property caninclude temperature or differential temperature. The physical orchemical property can include temperature or differential temperature,wherein an echo drift due to temperature ranges up to, and inclusive of,100 ns, or 0 ns. The maximum variation in temperature can range up to200 K. While temperature sensing is described, other properties,physical and chemical are contemplated.

As described in greater detail below, each sensor includes aninter-digitated transducer to excite and subsequently detect surfacewaves, and one or more reflector groups to diffract and reflect surfacewaves back towards the inter-digitated transducer, and wherein the oneor more reflector groups are spaced apart a pre-determined distancealong a wave propagation path from the inter-digitated transducer. Theinter-digitated transducer includes two interlaced comb-like metalstructures formed on the surface of a piezoelectric substrate, and theone or more reflectors include one or more groupings of one or morespaced apart metal line formed on the piezoelectric substrate. Further,the inter-digitated transducer can be coupled to at least one antennafor receiving and transmitting signals between each sensor and thereader system. The at least one antenna can be designed to an impedanceof 50 Ohms. The electrical impedance of the inter-digitated transducercan be substantially matched to the electrical impedance of the at leastone antenna at a frequency within the designated frequency band. And,the spectral range of the designated frequency band, such as the firstfrequency band, can be less than 100 MHz, or 50 MHz. The at least oneantenna can include a meander antenna, a monopole or dipole antenna, orother antenna, as listed below.

The inter-digitated transducer can include 10 to 20 pairs ofinter-digitated electrode pairs, or 15 inter-digitated pairs, forexample. The inter-digitated transducer can include two or more groupsof inter-digitated electrode pairs, and wherein each group ofinter-digitated electrode pairs is designed with a different electrodepitch. The single high frequency interrogation sequence can includeinterrogating sensors with a time-resolved excitation signal andprocessing received echo signals in the time domain, or with a frequencymodulated excitation signal and processing received echo signals in thefrequency domain.

When the physical or chemical property includes temperature, each sensorcan exhibit a temperature coefficient of delay (TCD) equal to or greaterthan 30 ppm-K⁻1, or 50 ppm-K⁻¹, or 75 ppm-K⁻¹, or 100 ppm-K⁻¹.

As mentioned, the one or more reflectors of each sensor can be arrangedto produce an impulse response signal in the time domain exhibiting atrain of two or more distinct echo impulse responses. The one or morereflectors of each sensor can be arranged to produce a first echoimpulse response for each sensor that is received by the reader systemin a first time delay range, and a second echo impulse response for eachsensor that is received by the reader system in a second time delayrange, the second time delay consecutive to the first time delayfollowing a first guard time delay inserted there between. And, thefirst guard time delay can range up to 200 ns, or range from 100 ns to200 ns.

The one or more reflectors of each sensor can be arranged to produce animpulse response signal in the time domain exhibiting a train of threeor more distinct echo impulse responses. And, the one or more reflectorsof each sensor can be arranged to produce a third echo impulse responsefor each sensor that is received by the reader system in a third timedelay range, the third time delay consecutive to the second time delayfollowing a second guard time delay inserted there between. The secondguard time delay can range up to 200 ns, or range from 100 ns to 200 ns.The first, second, and third time delay can range up to 5 microseconds.

The reader system 120 can include a radio frequency (RF) filter toreject signals at frequencies outside the designated frequency band. Theradio frequency (RF) filter can be designed to reject signals atfrequencies outside the designated frequency band. For example, the RFfilter can reject signals originating from harmonic frequencies of theplasma excitation frequency by excess of 30 dB, or even 40 dB.

While first plural sensors are described, second plural sensors can bemounted on or within the semiconductor device manufacturing system 100,wherein each sensor is assigned to a different region to monitor aphysical or chemical property of the assigned region of the system, andwherein the second plural sensors are made operable in the secondfrequency band according to design rules that permit the simultaneousinterrogation without collision between the response signals echoed fromeach sensor.

FIG. 1C schematically illustrates a reader system, including atransmitter circuit 141, a receiver circuit 142, a sampling circuit 143,memory 144, and a controller 145 to control sensor interrogation, managesignal processing to and from each component, and assess the processingstate of the semiconductor device manufacturing system 100.

According to yet another embodiment, a method for real-time sensing ofproperties in semiconductor device manufacturing equipment is described.The method is depicted in FIG. 2, and includes: locating a workpiecehaving plural sensors mounted thereon within a processing environment ofan semiconductor device manufacturing system in 210; assigning agrouping of sensors to a frequency band for interrogation of thegrouping in 220; and simultaneously and wirelessly interrogating eachgrouping of sensors using a single high frequency interrogation sequencein 230 that includes (1) transmitting a request pulse signal to theplural sensors designated with a sensor grouping, the request pulsesignal being associated with a designated frequency band, and (2)receiving uniquely identifiable response signals from the plural sensorsthat provide real-time monitoring of variations in the physical orchemical property at each assigned region of workpiece 1.

As an example, a sensing system is described below for monitoringtemperature or differential temperature. The wafer-type sensor caninclude a workpiece, onto which a plurality of temperature measurementsensors are connected. The temperature measurement sensors can includesurface acoustic wave (SAW) delay line sensors or SAW resonator sensors,each of which are connected to a proper antenna. The sensors are locatedaccording to the desired temperature mapping required for the workpieceor process. The SAW sensors can be based on delay lines designed in sucha way that they can be interrogated simultaneously with one or more,including a single, high frequency interrogation sequence that mayinclude either (i) a time-resolved excitation and signal processing, or(ii) a frequency-modulated continuous-wave (FMCW) approach. In thelatter, the frequency-modulated continuous wave approach can includeFourier signal processing to convolve and de-convolve information infrequency or wave-number space.

The SAW delay lines can be designed to match, or substantially match,the antenna impedance across a range of temperature and sensorperformance. A burst signal can be used when the interrogation and thesignal processing are time-resolved with a duration equal to, orapproximately equal to, the inverse of the width of the frequency bandof the transducer (i.e., a number of oscillations equal to the number ofthe finger pairs of the transducer). The SAW sensor can be designed insuch a way that several sensors can be interrogated simultaneouslywithout collision, shifting the sensor response in time in a way thatavoids any pulse superposition on the whole operating ranges andconditions.

Design rules are given to explain how this design is achieved usingRayleigh-like SAW on lithium niobate (LiNbO₃), as an example, withoutgenerality restriction. The use of a silica passivation layer can allowfor controlling the actual temperature sensitivity, theelectromechanical coupling, and the reflection coefficient of thesensor. The number of sensors that can be interrogated without collisioncan be increased significantly by using frequency bands shifted in sucha way that the interrogation of one set of sensors in a given band willpoorly couple energy in another band and preventing any cross-couplingby using a filter on the reader reception stage filtering the currentlyused band, i.e., only allowing the signal in the band to be received andprocessed. This filtering operation also allows for improving the signalprocessing during the application of the plasma, which generates RF(radio frequency) harmonics at a level that can pollute or perturb thesensor response signal processing, notably when the plasma excitationovercomes some tens of Watts, as observed by the inventors.

In another embodiment, the apparatus includes protection for the SAWsensor surface from plasma and/or corrosive chemistry, including ionicimpact during plasma excitation, which can irreversibly damage thesensors, the electrodes, and surface quality, thus reducing the sensorlife time.

In another embodiment, the apparatus includes an in-situ piezoelectricfilm deposited onto a silicon (Si) wafer surface, wherein the antenna isbonded onto the sensor location, allowing for both RF signal receptionand emission, and sensor surface protection. As described above, thewafer-type sensor can be composed of SAW devices with associated antennahaving one or more of the following features: (i) the use of SAW-tagdelay lines built on LiNbO₃ with similar time response shifted in such away that several sensors can be interrogated without collision/signalsuperposition; (ii) the use of several frequency bands to increase thenumber of sensors that can be interrogated onto a given wafer, usingadapted filters to improve the robustness of the signal processing, thusavoiding cross-coupling between the different frequency bands and themitigation of RF pollution due to the plasma excitation; (iii) the useof an adapted structure to allow for the wafer to be used even duringplasma activation (several structures are considered that provideprotection of the sensor); and (iv) the use of a single crystalpiezoelectric film bonded onto the wafer to form the SAW sensors thatcan be protected using the antenna.

Information provided herein referring to or concerning cut angles andcrystal orientation can be ascertained in the IEEE Std-176 standard onpiezoelectricity (ANSI/IEEE Std 176-1987 IEEE Standard onPiezoelectricity,http://standards.ieee.org/reading/ieee/std_public/description/ultrasonics/176-1987_desc.html).The material constants used for all the computations are those ofKovacs, et al. for lithium tantalate and niobate (G. Kovacs, M. Anhorn,H. E. Engan, G. Visintini, C. C. W. Ruppel, “Improved material constantsfor LiNbO₃ and LiTaO₃”, Proc. of the IEEE Ultrasonics Symposium,435-438, 1990). Data for Silicon (mass density and elastic/thermoelasticconstants) can be found in Landolt-Bornstein, as well as for fusedquartz (silica) and aluminum (Landolt-Bornstein, Numerical data andfunctional relationships in science and technology, Group III, Crystaland solid state physics, Vol. 11, K. H. Hellwege, and A. M. Hellwege,Eds., Springer-Verlag Berlin-Heidelberg-New York 1979). The sensitivityof the delay to temperature is classically given (cf. for instanceLeonhard Reindl et al, Theory and Application of Passive SAW RadioTransponders as Sensors, IEEE Trans. on UFFC, Vol. 45, No. 5, pp.1281-1292, 1998) by a Taylor expansion of the delay defined as follows:

f ₀ =f _(x)(1+^(θ)α(T−T ₀))   (1)

where f the current frequency at temperature T is given by the ration ofthe wave velocity V divided by the wavelength λ and f₀ the frequency atreference temperature T₀=25° C. Now defining r the delay of a wavetraveling from a transducer to a reflector and back to the transduceras:

τ=L/V=L/(λf)   (2)

we can express the delay at a given temperature T as follows:

Δτ/τ=ΔL/L−(Δλ/λ+Δf/f) with Δτ=τ−τ₀   (3)

with L=L₀×(1+α₁ ⁽¹⁾(T−T₀)) and λ=λ₀×(1+α₁ ⁽¹⁾(T−T₀)) and α₁ ⁽¹⁾ thefirst order thermal expansion coefficient. Assuming that ΔL/L=Δλ/λ≅α₁⁽¹⁾(T−T₀) allows on for demonstrating that:

Δτ/τ=−(Δf/f)   (4)

and, as a consequence, the temperature coefficient of delay (TCD) is theinverse of the temperature coefficient of frequency (TCF). In oneembodiment, the use of real-time sensing includes temperaturemeasurement using SAW-tags based on an inter-digitated transducer (IDT)to excite and detect the surface waves, and reflector groups locatedalong the wave propagation path, diffracting and launching waves backtoward the transducer. Although the above consideration holds forresonator-based sensors, other design rules than the following rules arenecessary for such sensors.

In the case of LiNbO₃ cuts used for SAW tag application (which can be(YX/)/128° or (YZ) cuts), the TCF classically lies in the range[−80;−90] ppm-K⁻¹. The TCD value can range up to a value of 100 ppm-K⁻¹as the maximum delay variation due to temperature. The inventorsrecognize this parameter as one method to set the delay range in which agiven echo can vary. The above mentioned TCD can be used to set theminimum delay between two echoes to avoid any signal superposition(collision) and prevent clear and efficient differentiation during themeasurement process.

FIG. 3 provides a simplified schematic of a SAW-tag sensor 300 withinter-digitated transducer (IDT) 301, with slots provided as reflectors302 positioned in groups for a given delay range. Assuming two delays,τ₁ and τ₂, close to one another, a fundamental design rule can include asensor designed to avoid the overlap of the two corresponding echoes. Inthat purpose, an important parameter to take into account is the echospreading. This parameter is related to the transducer length and thedelay line operation. Actually, one must consider that the form of theecho on the impulse response of the SAW-tag results from theself-convolution of the impulse response of the transducer prolongatedby the number of electrodes in a given reflector.

In the case of SAW-tags designed and fabricated on LiNbO₃ (YX/)/128°,considering an aperture of 70 μm, the number of electrode pairs in thetransducer can be limited to 15 to achieve an electrical impedance closeto 50 Ohms on the whole operation spectrum (we consider here the 2.45GHz-centered ISM band regulation for generality reason). This designconsideration equates to a spectrum range set to 85 MHz, yielding aminimum length of 30 oscillations to avoid the spectrum overcoming theabove mentioned value. The duration of such an excitation burst can beabout 12 ns (whereas only about 6 ns would be mandatory using a15-finger-pair IDT to couple the energy at maximum, i.e., the transducerand excitation spectrum overlaps at best), which makes the length of theself-convolution equal to 24 ns, majored to 25 ns in FIG. 3 forconvenience.

Referring again the two above-mentioned echoes, the minimum durationbetween the echoes can be set to avoid any overlap of their signature onthe whole temperature range. A 100° C. temperature variation can resultin a 10⁻² relative change in the nominal value of the delay. Therefore,when two sensors are submitted to a temperature difference of 200° C.,the delay between the two echoes is expected to be at minimum 2% of thenominal longest delay (for instance, τ₂, if we assume τ₁<τ₂) plus 25 ns,the maximum time spreading of one echo. As an example, a 30 ns echoseparation can be selected because the spreading of one echo does notovercome 20 ns. For illustration purpose, if a 500 ns delay isconsidered for T₂, the above rule infers that τ₁ correspond to a maximumdelay of 465 ns (i.e., 500−10−25 ns). This exercise provides a generaldesign rule which allows a design to comply with ISM regulations, andaddress the separation of two echoes when measuring several sensors atonce.

Therefore, as an example, if fifteen (15) sensors are to be interrogatedsimultaneously, once the initial delay τ₀ of the first sensor (the onewhich “answers” first) is fixed, all of the first echoes of the sensorswill arise in a minimum of τ₀ plus 35 ns times 15 delay range (e.g.,τ₀+525 ns), guaranteeing that the sensor set can be interrogated and theresponse read without collision on the whole temperature range. After aminimum guard delay following the last sensor's first echo (the firstecho of the sensor “answering” last), the same analysis can be appliedfor the second echo of the sensors. This guard delay, of course, canovercome the delay between the two “first” echoes, the above-mentioned35 ns, otherwise it is difficult to differentiate the pulse train of thefirst echo and the pulse train of the second echo. This delay could betypically 50 ns, but for more signal process robustness a delay rangingbetween 100 and 200 ns can be used. As another example, a delay of 150ns can be used to provide a difference of delay sufficiently long toavoid confusion between the first and second pulse trains, and yield awave path sufficiently short to minimize losses due to wave propagation(10⁻² dB/λ can be typical as a loss parameter on (YX/)/128° LiNbO₃surface which is validated when comparing theoretical and experimentalSAW-tag responses).

According to an example, in consideration of the design rules outlinedabove for a SAW device, a wafer-type sensor can include four (4)groupings of sixteen (16) sensors assigned to a separate frequency band.FIGS. 4A through 4D show the typical responses of a grouping of sixteen(16) sensors superimposed to elucidate the sequence of peaks, includingthe first and second echoes (see FIG. 4A), and the separation betweenthe peaks (see the close-up of the first three echoes in FIG. 4B). InFIG. 4C, the result of summing all the delay line S₁₁ parameters isplotted, and the corresponding time response is computed. For the sakeof comparison, one of the delay line time-domain responses issuperimposed to illustrate the actual effect of the summation: e.g., thebaseline is increased, meaning that the signal-to-noise ratio isdecreased, yet not sufficiently degraded to prevent the system operation(as illustrated in FIG. 4C).

The interrogation of sixty five (65) sensors on a single wafer can beachieved by fabricating four sets of sixteen (16) sensors operating indifferent frequency bands (plus one in one of the four frequency bands).Using IDTs composed of 15 finger-pairs, the spectrum spreading of theSAW-tag is about 150 MHz (i.e., plus or minus 75 MHz from the centralfrequency). Therefore, according to one embodiment, the second, third,and fourth frequency bands can be shifted 150, 300 and 450 MHz,respectively, from the first frequency band to generate the three otherfrequency bands to complete the whole wafer-type sensor design. Theresulting spectral distribution is shown in FIG. 4D, allowing for aclear separation of each frequency band. As a consequence, the same(time-domain) echo distribution is preserved for each band, whichsimplifies the signal processing, since only the frequency band has tobe shifted (i.e., the local oscillator of the interrogator), as well asthe reception filter which must correspond to the current treated band.

Consequently, the interrogation process for addressing sixty five (65)measurement points onto the wafer can include setting the centralfrequency to the central frequency of the first band (i.e., set thelocal oscillator and the reception filter to the current frequencyband), to set the reader in emission mode and to launch the RFinterrogation signal to the reader antenna, to switch the reader to thereception mode after the emission of the whole interrogation signal(e.g., 15 ns max for a 15-finger-pair IDT, corresponding to 15 signalperiods plus some delay to fade the antenna contribution properly), andto collect the signals re-emitted by the sensors (e.g., max delay about2 μs), to repeat the operation as much as the signal must be averaged toimprove the SNR, and then to set the next frequency band and repeat theoperation as long as the four bands have not been scanned.

Note that the first computations were made considering a two-echosolution. However, the same design process can be applied to a threepulse sensor that will allow meeting desired accuracy targets. In thatperspective, an effort can be achieved to optimize the sensor responseaccording the measurements achieved, and more particularly, optimizingthe transducer performance. Several approaches can be taken, includingvarying the period in the IDT to cover the whole 2.4-2.5 GHz band, andto slightly shift the reflectors so that they do not actually exhibitthe same reflection spectral coverage. For instance, the IDT can besplit into five (5) sections (see FIG. 5; or more or less than five (5))for which the mechanical period is set respectively to p_(IDT1)=0.78 nm(λ=1.56 μm), p_(IDT2)=785 nm (λ=1.57 μm), p_(IDT3)=790 nm (λ=1.58 μm),p_(IDT4)=795 nm (λ=1.59 μm), and p_(IDT5)=800 nm (λ=1.6 μm), consideringa metal thickness of 100 nm (relative electrode height h/λ in excess of6%) and a metal ratio of 0.45. The IDT the consists of a first electrodepair at p_(IDT1), two electrode pairs set at p_(IDT2), five electrodepairs at p_(IDT3), four electrode pairs at p_(IDT4) and three atp_(IDT5).

Along this distribution, the impedance of the transducer remains closeto approximately 50Ω, a design condition for optimizing the energytransmission from the antenna to the SAW device and vice versa. Severalother configurations can be imagined; however, the leading idea is tospread the IDT optimal response on a band larger than the one obtainedconsidering a purely synchronous IDT structure at λ=1.57 μm (see FIGS.6A and 6B). On the other hand, three groups of reflectors can be usedaccording to the above remark (improving the sensor resolution andremoving phase uncertainties), two groups on one side of the reflectorand one group on the other side of the reflector to optimize the sensorresponse. The mechanical period of each group can, respectively, be setto p_(R1)=780 nm and p_(R2)=790 nm with a metal ratio set to 0.55. Ascheme is reported to illustrate the SAW-tag concept.

The choice of a metal ratio of 0.45, for example, in the IDT can beselected to reduce or minimize reflection phenomena (reflectioncoefficient smaller than 3% on a single obstacle) inside the transducer,whereas the reflector metal ratio can be set to 0.55, yielding areflection coefficient on a single obstacle close to 5%. The metal ratiocan range from 0.4 to 0.6, for example (the minimal width of theelectrode can be equal to 351 nm for a metal ratio of 0.45 and a periodp₁=0.78). Using this electrode distribution, a balanced distribution ofthe SAW-tag response can be achieved with all the three pulses (echoes)of the delay lines close to −20 dB. In this assessment, the propagationloss can be about 10⁻³ dB/A for the selected 100 MHz band (from 2.4 to2.5 GHz).

According to an additional embodiment, another configuration can includea single phase uni-directional transducer (SPUDT) according to designspublished in Plessky, et al. (S. Lehtonen, V. P. Plessky, C. S.Hartmann, and M. M. Salomaa, “SPUDT filters for the 2.45 GHz ISM band”,IEEE Trans. Ultrason. Ferroelectr. Freq. Control 51, pp. 1697-1703,2004). Therein, the reflectors are located on one side of the IDT whichemits more energy in that direction than on the opposite one.

According to yet additional embodiments, the coupling and reflectivityof SAW-tag sensors based on Rayleigh waves on (YX//128°) LiNbO₃substrates can be adjusted by depositing a layer, such as a SiO₂ layer.An increase in the coupling can reduce the insertion loss and increasethe interrogation distance. In the same field of consideration, the useof pure shear waves for SAW-tags is also contemplated, wherein shearwaves can be guided by the deposition of a guiding film onto the SAWdevice.

According to various embodiments, numerous configurations arecontemplated for forming piezoelectric films, such as lithium niobate,lithium tantalite, or langasite, on the workpiece, including siliconworkpieces. Piezoelectric films can be formed by wafer molecular bondingand lapping/polishing. Therein, piezoelectric films are bonded andthinned, or transferred onto silicon, allowing for the excitation ofguided modes (true surface waves) without radiation losses in thesubstrate underneath the film (the wave is guided by the siliconsubstrate) exhibiting an electromechanical coupling k_(s) ² (for which1−(f_(r)/f_(a))² with f^(r) and f_(a) the resonance and anti-resonancefrequencies of the mode signature respectively provides a reliableestimation, provided the mode is not mixing energy with other guidedmodes nor waves radiated from the surface) in excess of 3% and areflection coefficient on a single obstacle at minimum equal to 3%.Several examples can be provided to determine the actual configurationsfor shear waves on LiTaO₃ (YX/)/32° to (YX/)/48° and on several othersingly rotated lithium tantalate cuts onto silicon (or sapphire or anysubstrate allowing wave guiding), and Rayleigh waves on LiNbO₃(YX/)/128° and shear waves on almost all the singly rotated lithiumniobate cuts onto silicon are contemplated.

More generally, for a material film, such as LiNbO₃, transferred ontosilicon, shear waves can be used for all the propagation directions,excluding propagation directions ranging from 100° to 140°, whereasRayleigh waves can be used in the propagation direction range from 100°to 180°. The preferred solutions for shear waves correspond topropagation directions ranging from 0° to 20° and from 140° to 180° topromote a large absolute value of TCF (yielding a TCD value in excess of60 ppm−K⁻¹). Note that for fundamental symmetry reasons, the propertiesof the waves are the same when adding 180° to the angle θ (rotationaround X crystallographic axis, referring the IEEE Std-176 standard) ofa given singly-rotated cut. To maximize the SAW-tag operation, one canselect a propagation direction from −20° to +20° because theelectromechanical coupling is maximum (in excess of 20%). It is noted,however, that these design considerations allow for second orderimprovements, since most of the crystal cuts can be used for theconsidered application, as mentioned above.

More generally, for a material film, such as LiTaO₃, transferred ontosilicon, the shear wave mode is exploitable for a propagation directionranging from −30° to +90°. Moreover, the TCF is particularly favorablefor a temperature sensor in the angular range of −30° to 0° for whichthe coupling factor is ranging from 3 to 8%. According to a preferredembodiment, when considering the coupling factor, the cut can be nearthe (YX/)/36° for which the TCF is close to zero. This orientationfamily can be considered for the measurement of a broad range ofproperties, yet is less optimal for temperature.

FIG. 7 shows an example of a SAW-tag operating near 2.45 GHz,manufactured of a material film, such as LiNbO₃, transferred ontosilicon. Device 700 includes interdigitated transducer 701, antenna 702,and reflector groups 703. FIG. 8 shows exemplary reflection coefficient|S11| in time domain for eight (8) SAW-tag sensors operating at roomtemperature (approximately 20 degrees C.) in the 2.4 to 2.5 GHzfrequency band. FIG. 9 shows exemplary reflection coefficient |S11| intime domain for thirteen (13) SAW-tag sensors operating at 60 degrees C.in the 2.4 to 2.5 GHz frequency band.

According to various embodiments, the antenna design for the sensors caninclude single pole designs, dipole designs, helical designs, circulardesigns, spiral designs, patch designs, or meander designs, or anycombination of two or more thereof. FIG. 10 illustrates a meander-typeantenna, illustrating several dimensions to be selected for the antennadesign. Metallization of the antenna can produce an antenna thicknessranging up to 50 micron, or up to 35 micron (e.g., ranging from 10 to 35micron in thickness). The antenna may be composed of Al, Cu, Ni, Au, oralloys thereof. The antenna can be fabricated using a variety ofdeposition techniques, including electroplating.

In several embodiments, the wafer-type sensor can be operated duringexposition to plasma. The upper, exposed surface of the device can beexposed to plasma, including plasma chemistry and ion bombardment. As aresult, if unprotected, the device can be etched. Therefore, protectionof the SAW-tag and the antenna, while operating the sensor under plasmaconditions for more than several of minutes (e.g., up to 5-10 minutes)is contemplated according to several embodiments. The wafer-type sensorthickness can range up to 5 mm (millimeters), preferably up to 2 mm,more preferably up to 1.5 mm, and most preferably up to 1.2 mm. In someembodiments, the sensors include a protective cover, such as an etchedglass cover, and in other embodiments, the sensors are embedded in thesubstrate, such as a silicon substrate.

According to one embodiment shown in FIG. 11, a SAW-tag and its antennaare manufactured separately, and then bonded onto a silicon substrate.The device is connected using wire bonding, and protected by aprotective layer, such as a machined glass cover. Since the protectivecover is an electrical insulator, the connection wire may be in contactwith the cover. It is then bonded onto the silicon substrate to form ahermetically sealed cavity. This operation should be operated undervacuum, or at least under a dry air condition, to reduce or avoid anyoxygen trapped in the cavity.

According to another embodiment shown in FIG. 12, a SAW-tag and itsantenna are manufactured on the same substrate, and then bonded onto asilicon substrate. The device is protected a protective layer, such as amachined glass cover.

According to another embodiment shown in FIG. 13, a SAW-tag and itsantenna are fabricated in a manner similar to the device depicted inFIGS. 11 and 12. However, in this embodiment, the silicon substrate isetched to allow locating and recessing the SAW-tag and antenna devicewithin the silicon substrate, i.e., at least partially or fully recessedbeneath an upper surface of the silicon substrate. As a result, theprotective layer can include a planar cover, such as a glass plate orsheet.

According to another embodiment shown in FIG. 14, a SAW-tag and itsantenna are fabricated directly on a silicon substrate. Fabrication ofthe device directly on the silicon substrate can include etching anddeposition techniques, with appropriate patterning to remove and addmaterial to the silicon substrate. Each device is independently coveredwith a protective layer, using for example an adapted silica mark.

According to another embodiment shown in FIG. 15, a SAW-tag and itsantenna are fabricated directly on a silicon substrate. However, eachdevice is covered with a full-substrate protective layer, such as aglass cover plate.

According to yet another embodiment shown in FIG. 16, a SAW-tag and itsantenna are fabricated silicon, the SAW-tag being manufactured on LiNbO₃or LiTaO₃, for example, and then assembled and bonded onto the siliconsubstrate. The SAW-tag sensor and its antenna can be protected by amachined (etched) Silica plate.

In other embodiments, plural sensors can be fabricated on a LiNbO₃ orLiTaO₃ substrate, and then bonded to or embedded within a siliconsubstrate. The technique of flip-chip can also be exploited to build thedevice(s) mounted onto a silicon substrate. The antenna can be directlyfabricated onto the silicon substrate, followed by flip-chipping theSAW-tag proximate the antenna to reduce undesired parasitic capacitanceor self-inductance due to wire bonding. The use of a flip chip approachcan be compatible with the application as the back of the SAW-tag willbe exposed to the processing environment, such as plasma, but not thefront side.

While the device, including sensor and/or antenna, can be fabricated ona semiconductor substrate, such as a silicon substrate, other materialsand substrates are contemplated. The substrate may be an insulator, aconductor, or a semiconductor. The substrate may include any materialportion or structure of a device, particularly a semiconductor or otherelectronics device, and may, for example, be a base substrate structure,such as a semiconductor substrate or a layer on or overlying a basesubstrate structure such as a thin film. The substrate may be aconventional silicon substrate or other bulk substrate comprising alayer of semi-conductive material. As used herein, the term “bulk wsubstrate ” means and includes not only silicon wafers, but alsosilicon-on-insulator (“SOI”) substrates, such as silicon-on-sapphire(“SOS”) substrates and silicon-on-glass (“SOG”) substrates, epitaxiallayers of silicon on a base semiconductor foundation, and othersemiconductor or optoelectronic materials, such as silicon-germanium,germanium, gallium arsenide, gallium nitride, and indium phosphide. Thesubstrate may be doped or undoped. Thus, substrate is not intended to belimited to any particular base structure, underlying layer or overlyinglayer, patterned or un-patterned, but rather, is contemplated to includeany such layer or base structure, and any combination of layers and/orbase structures.

As the sensor can be required to operate during plasma operation, theseembodiments can account for radio frequency (RF) electromagnetic fieldsused to generate plasma in a vacuum environment. RF operation can rangefrom the low MHz frequencies (e.g., 1 MHz) to very high frequency (VHF)operation (e.g., 100 MHz). As a result of the nonlinear behavior ofplasma, harmonics of the excitation frequency are produced, which canimpact the operation of a SAW-tag sensor at frequencies near the 434-MHzcentered and 2.45-GHz centered ISM bands. To accommodate, signalfiltering can be employed to eliminate harmonic contribution to thedetected signal. As an example, when the RF excitation frequency isabout 13.56 MHz, the harmonic content as a result of plasma isrelatively inconsequential within the 2.45 GHz region (and moregenerally above 2 GHz). However, at higher RF excitation frequencies,harmonic content may be more important, and impact sensor operation.Even with favorable conditions corresponding to an operation above 2GHz, RF filtering can be used to reject all unwanted contributions dueto the plasma source, and the inventors have observed successfulmonitoring of SAW devices with active plasma conditions, particularlywhen the plasma power overcomes 70 Watts (W). For example, RF filteringcan be employed for plasma power conditions exceeding 50 W.

As noted previously, the above describes an apparatus for real-timesensing of properties in electronic device manufacturing, according toseveral embodiments. The electronic device manufacturing system caninclude semiconductor device equipment capable of processing asubstrate, such as a 200 mm or 300 mm substrate, in a gas-phaseenvironment, that may or may not include plasma. In semiconductormanufacturing, plasma can be used to assist the deposition of materialonto a substrate, or the etching of material from the substrate.Examples of plasma processing systems, for either deposition, oretching, or both deposition and etching are described below and depictedin FIGS. 17A through 17D.

FIGS. 17A through 17D provide several plasma processing systems that maybe used to facilitate plasma-excitation of a process gas. FIG. 17Aillustrates a capacitively coupled plasma (CCP) system, wherein plasmais formed proximate a substrate between an upper plate electrode (UEL)and a lower plate electrode (LEL), the lower electrode also serving asan electrostatic chuck (ESC) to support and retain the substrate. Plasmais formed by coupling radio frequency (RF) power to at least one of theelectrodes. As shown in FIG. 17A, RF power is coupled to both the upperand lower electrodes, and the power coupling may include differing RFfrequencies. Alternatively, multiple RF power sources may be coupled tothe same electrode. Moreover, direct current (DC) power may be coupledto the upper electrode.

FIG. 17B illustrates an inductively coupled plasma (ICP) system, whereinplasma is formed proximate a substrate between an inductive element(e.g., a planar, or solenoidal/helical coil) and a lower plate electrode(LEL), the lower electrode also serving as an electrostatic chuck (ESC)to support and retain the substrate. Plasma is formed by coupling radiofrequency (RF) power to the inductive coupling element. As shown in FIG.17B, RF power is coupled to both the inductive element and lowerelectrode, and the power coupling may include differing RF frequencies.

FIG. 17C illustrates a surface wave plasma (SWP) system, wherein plasmais formed proximate a substrate between a slotted plane antenna and alower plate electrode (LEL), the lower electrode also serving as anelectrostatic chuck (ESC) to support and retain the substrate. Plasma isformed by coupling radio frequency (RF) power at microwave frequenciesthrough a waveguide and coaxial line to the slotted plane antenna. Asshown in FIG. 17C, RF power is coupled to both the slotted plane antennaand lower electrode, and the power coupling may include differing RFfrequencies.

FIG. 17D illustrates remote plasma system, wherein plasma is formed in aregion remote from a substrate and separated from the substrate by afilter arranged to impede the transport of charged particles from theremote plasma source to a processing region proximate the substrate. Thesubstrate is supported by a lower plate electrode (LEL) that also servesas an electrostatic chuck (ESC) to retain the substrate. Plasma isformed by coupling radio frequency (RF) power to a plasma generatingdevice adjacent the remotely located region. As shown in FIG. 9D, RFpower is coupled to both the plasma generating device adjacent theremote region and lower electrode, and the power coupling may includediffering RF frequencies.

While not shown, the plasma processing systems of FIGS. 17A through 17Dcan include other componentry, including coated and replaceable partsdesign to protect interior surfaces of the processing chamber. Suchparts can include deposition shields, baffle plate assemblies,confinement shields, etc., that surround the processing environment andpotentially interfere with signal exchange between the interrogator andthe instrumented substrate.

The plasma processing systems of FIGS. 17A through 17D are intended tobe illustrative of various techniques for implementing the steppedion/radical process described. Other embodiments are contemplatedincluding both combinations and variations of the systems described.

In the claims below, any of the dependents limitations can depend fromany of the independent claims.

In the preceding description, specific details have been set forth, suchas a particular geometry of a processing system and descriptions ofvarious components and processes used therein. It should be understood,however, that techniques herein may be practiced in other embodimentsthat depart from these specific details, and that such details are forpurposes of explanation and not limitation. Embodiments disclosed hereinhave been described with reference to the accompanying drawings.Similarly, for purposes of explanation, specific numbers, materials, andconfigurations have been set forth in order to provide a thoroughunderstanding. Nevertheless, embodiments may be practiced without suchspecific details. Components having substantially the same functionalconstructions are denoted by like reference characters, and thus anyredundant descriptions may be omitted.

Various techniques have been described as multiple discrete operationsto assist in understanding the various embodiments. The order ofdescription should not be construed as to imply that these operationsare necessarily order dependent. Indeed, these operations need not beperformed in the order of presentation. Operations described may beperformed in a different order than the described embodiment. Variousadditional operations may be performed and/or described operations maybe omitted in additional embodiments.

“Workpiece”, “Substrate”, or “target substrate” as used hereingenerically refers to an object being processed in accordance with theinvention. The substrate may include any material portion or structureof a device, particularly a semiconductor or other electronics device,and may, for example, be a base substrate structure, such as asemiconductor wafer, reticle, or a layer on or overlying a basesubstrate structure such as a thin film. Thus, substrate is not limitedto any particular base structure, underlying layer or overlying layer,patterned or un-patterned, but rather, is contemplated to include anysuch layer or base structure, and any combination of layers and/or basestructures. The description may reference particular types ofsubstrates, but this is for illustrative purposes only.

Those skilled in the art will also understand that there can be manyvariations made to the operations of the techniques explained abovewhile still achieving the same objectives of the invention. Suchvariations are intended to be covered by the scope of this disclosure.As such, the foregoing descriptions of embodiments of the invention arenot intended to be limiting. Rather, any limitations to embodiments ofthe invention are presented in the following claims.

1. An apparatus for real-time sensing of properties within industrialmanufacturing equipment, comprising: first plural sensors mounted withina processing environment of a manufacturing system, each sensor beingassigned to a different region to monitor at least one of a physical,chemical, or electrical property of the assigned region of the system;and a reader system having componentry configured to simultaneously andwirelessly interrogate the first plural sensors using a single highfrequency interrogation sequence that includes (1) transmitting a firstrequest pulse signal to the first plural sensors, the first requestpulse signal being associated with a first frequency band, and (2)receiving uniquely identifiable response signals from the first pluralsensors that provide real-time monitoring of variations in the at leastone of a physical, chemical, or electrical property at each assignedregion of the system, wherein the first plural sensors are made operablein the first frequency band according to design rules that permit thesimultaneous interrogation without collision between the responsesignals echoed from each sensor operating in the first frequency band,wherein the processing environment includes a gas-phase plasmaenvironment, and wherein the first frequency band is defined to excludeharmonic frequencies of the plasma excitation frequency.
 2. Theapparatus of claim 1, wherein the manufacturing system includes asemiconductor manufacturing system, or a non-semiconductor manufacturingsystem.
 3. The apparatus of claim 2, wherein the manufacturing systemfacilitates manufacturing of semiconductor devices, photonic devices,photo-emission devices, photo-absorption devices, or photo-detectiondevices.
 4. The apparatus of claim 2, wherein the manufacturing systemfacilitates manufacturing of metallic, semi-metallic, non-metallic,polymeric, plastic, ceramic, or glass or glass-like workpieces.
 5. Theapparatus of claim 1, further comprising: a workpiece to be arrangedwithin the processing environment of the manufacturing system, whereinthe first plural sensors are mounted on the workpiece.
 6. The apparatusof claim 1, further comprising: multiple sensor groupings assigned toplural, uniquely defined frequency bands, the multiple sensor groupingsincluding the first plural sensors assigned to the first frequency band.7. The apparatus of claim 1, wherein each sensor includes a surfaceacoustic wave (SAW) delay line device, and wherein the substrateincludes LiNbO₃, LiTaO₃, or La₃Ga₅SiO₁₄.
 8. The apparatus of claim 1,wherein the at least one of a physical or chemical property includestemperature or differential temperature.
 9. The apparatus of claim 1,wherein each sensor includes an inter-digitated transducer to excite andsubsequently detect surface waves, and one or more reflector groups todiffract and reflect surface waves back towards the inter-digitatedtransducer, and wherein the one or more reflector groups are spacedapart a pre-determined distance along a wave propagation path from theinter-digitated transducer.
 10. The apparatus of claim 9, wherein theinter-digitated transducer is coupled to at least one antenna forreceiving and transmitting signals between each sensor and the readersystem.
 11. The apparatus of claim 9, wherein the one or more reflectorsof each sensor are arranged to produce an impulse response signal in thetime domain exhibiting a train of two or more distinct echo impulseresponses.
 12. The apparatus of claim 9, wherein the one or morereflector groups are located on the same side of the inter-digitatedtransducer.
 13. An apparatus for real-time sensing of properties withinindustrial manufacturing equipment, comprising: first plural sensorsmounted within a processing environment of a manufacturing system, eachsensor being assigned to a different region to monitor at least one of aphysical, chemical, or electrical property of the assigned region of thesystem; and a reader system having componentry configured tosimultaneously and wirelessly interrogate the first plural sensors usinga single high frequency interrogation sequence that includes (1)transmitting a first request pulse signal to the first plural sensors,the first request pulse signal being associated with a first frequencyband, and (2) receiving uniquely identifiable response signals from thefirst plural sensors that provide real-time monitoring of variations inthe at least one of a physical or chemical property at each assignedregion of the system, wherein the first plural sensors are made operablein the first frequency band according to design rules that permit thesimultaneous interrogation without collision between the responsesignals echoed from each sensor operating in the first frequency band,and wherein each sensor of the first plural sensors includes aninter-digitated transducer to excite and subsequently detect surfacewaves, and one or more reflector groups to diffract and reflect surfacewaves back towards the inter-digitated transducer, and wherein the oneor more reflector groups are spaced apart a pre-determined distancealong a wave propagation path from the inter-digitated transducer. 14.The apparatus of claim 13, wherein the inter-digitated transducer iscoupled to at least one antenna for receiving and transmitting signalsbetween each sensor and the reader system.
 15. The apparatus of claim13, wherein the one or more reflectors of each sensor are arranged toproduce an impulse response signal in the time domain exhibiting a trainof two or more distinct echo impulse responses.
 16. The apparatus ofclaim 13, wherein the one or more reflector groups are located on thesame side of the inter-digitated transducer.
 17. An apparatus forreal-time sensing of properties within industrial manufacturingequipment, comprising: first plural sensors mounted within a processingenvironment of a manufacturing system, each sensor being assigned to adifferent region to monitor at least one of a physical, chemical, orelectrical property of the assigned region of the system; and a readersystem having componentry configured to simultaneously and wirelesslyinterrogate the first plural sensors using a single high frequencyinterrogation sequence that includes (1) transmitting a first requestpulse signal to the first plural sensors, the first request pulse signalbeing associated with a first frequency band, and (2) receiving uniquelyidentifiable response signals from the first plural sensors that providereal-time monitoring of variations in the at least one of a physical orchemical property at each assigned region of the system, wherein thefirst plural sensors are made operable in the first frequency bandaccording to design rules that permit the simultaneous interrogationwithout collision between the response signals echoed from each sensoroperating in the first frequency band, and wherein the single highfrequency interrogation sequence includes interrogating sensors with atime-resolved excitation signal and processing received echo signals inthe time domain, or interrogating sensors with a frequency modulatedexcitation signal and processing received echo signals in the frequencydomain.
 18. An apparatus for real-time sensing of properties withinindustrial manufacturing equipment, comprising: first plural sensorsmounted within a processing environment of a manufacturing system, eachsensor being assigned to a different region to monitor at least one of aphysical or chemical property of the assigned region of the system; anda reader system having componentry configured to simultaneously andwirelessly interrogate the first plural sensors using a single highfrequency interrogation sequence that includes (1) transmitting a firstrequest pulse signal to the first plural sensors, the first requestpulse signal being associated with a first frequency band, and (2)receiving uniquely identifiable response signals from the first pluralsensors that provide real-time monitoring of variations in the at leastone of a physical or chemical property at each assigned region of thesystem, wherein the first plural sensors are made operable in the firstfrequency band according to design rules that permit the simultaneousinterrogation without collision between the response signals echoed fromeach sensor operating in the first frequency band, and wherein aprotective material covers the first plural sensors to insulate eachsensor from the environment present in the industrial manufacturingsystem.
 19. The apparatus of claim 18, wherein the processingenvironment includes a gas-phase plasma environment.
 20. The apparatusof claim 19, wherein the first frequency band is defined to excludeharmonic frequencies of the plasma excitation frequency.